<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title></title>
  <style>
    .video{
      margin: 0 auto;
      width: 320px;
      height:290px;
    }
  </style>
</head>
<body>

<div id="main">
  <img src="./images/u=1576788186,4000013657&fm=27&gp=0%20(1).jpg" alt="">
</div>


<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script><!--jQuery文件-->
<script>
  var body = document.getElementById('main');
  function addElement(){
    body.innerHTML = '<video class="video" controls style="z-index: 100;" id="video" autoplay>\n' +
      '  <source src="./mp4/国产优秀感人爱情动画短片《我们的世界》_腾讯视频.mp4" type="video/mp4">\n' +
      '</video>'
  }
  setTimeout("addElement()",3000);
  setTimeout(function () {
    console.log($(".video"))
  },3000)
</script>
</body>
</html>